Small electronic systems implemented as integrated circuits may have a single input pin for receiving a static digital control signal. Examples are electric power management systems such as DC/DC converters, charge pumps, linear regulators and battery chargers. These systems often have a “mode pin”, i.e. a single input pin for application of an external digital mode selection signal. In the case of a DC/DC converter, for example, a power saving mode of operation may be provided, and the converter is switched between a normal operating mode and the power saving mode by application of an external mode selection signal to the mode pin. Additionally, these systems usually need to be configured. Reverting to the example of a DC/DC converter, various settings such as output voltage, output current, current limitation etc. must be made. These settings are usually made with an external resistor network and associated switches, for example. An alternative is digital programming of the system. While digital programming is a desirable feature in terms of flexibility and reduction in the number of external components, current solutions require an I2C interface which needs considerable die space and adds considerably to the total system costs.